Fungicidal control of moulds

ABSTRACT

A composition for treating fungus infection of turfgrass, such as snow mold infection, comprises a mixture of fungicidally effective amounts of formulae 1 and 2: 
     
       
         
         
             
             
         
       
         
         
           
             and in particular mixtures of iprodione and trifloxystrobin. A method for treating snow molds comprises applying the mixture before the onset of continuous snow cover, in at least one application.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a §371 National Stage Application of International ApplicationNo. PCT/CA2005/001608 filed Oct. 19, 2005, which is incorporated hereinby reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the use of combinations of fungicidesto control mould and related fungus infestations in grasses. Inparticular the present invention relates to the used of combinations ofdicarboximide and 3-phenyl hydantoin fungicides and their formulations.

2. Description Of Related Art

Fine turfgrass species are grown on golf course greens, fairways and teeboxes, as well as turf farms and many other locations. In northernregions, such as Canada and the northern United States, which aresubject to temperate climates in the late summer and early fall and snowconditions in late fall and early winter certain moulds such as dollarspot, Sclerotinia homeocarpa, and snow moulds, such as Microdochiumnivale, Typhula incarnata and Typhula ishikariensis, represent a chronicproblem for turfgrass growers. If left untreated in the late summer andfall, turfgrass is predisposed to damage caused by Sclerotiniahomeocarpa in the late summer and fall and the snow moulds in late falland over winter to spring. Where the mould infection is extensive, therecovery of the turfgrass can be delayed well into the growing seasonand seriously affect the ability of the turfgrass to recover, leavingareas of dead patches. Further, turfgrasses weakened or damaged by thesemoulds are extremely slow to recover in the spring and are often invadedby undesirable opportunistic weedy grass species such as creepingbentgrass (Agrostis palustris) and annual bluegrass (Poa annua).

A typical snow mould prevention program requires a mould inhibitingfungicide to be applied to turfgrass prior to permanent winter snowcover. Typical programs consist of three applications prior to permanentsnow cover and an additional application after the snow cover is gone inthe spring. Several commercial fungicide products have been approved foruse against dollar spot and snow mould species, as will be describedbelow.

Another fungus infection that afflicts turfgrass is dollar spot, adisease of turfgrasses caused by the fungus Sclerotinia homeocarpa. Thisspecies attacks most turfgrasses grown in the South. Bentgrass, hybridbermudagrasses and zoysia are most susceptible to dollar spot. Thedisease occurs from spring through fall, and is most active during moistperiods of warm days (70-85° F.) and cool nights (60° F.) in the spring,early summer and fall.

Rovral Green GT™ (iprodione;3-(3,5-dichlorophenyl)-N-(1-methylethyl)-2,4-dioxo-1-imidazolidinecaboximide)is a dicarboximide fungicide registered in Canada for pink snow mouldcontrol at a rate of 250 ml/100 m² and for grey snow mould control at arate of 375 ml/100 m². Iprodione is a member of the class of 3-phenylhydantoin compounds described in U.S. Pat. No. 3,755,350 to Sauli. Theeffectiveness of iprodione to control the spread of snow mould inturfgrasses (especially the grey snow moulds T. incarnata and T.ishikariensis) is highly variable due to the varying amounts of fungusinoculums, the varying length of snow cover under which snow mouldinoculums thrive and the varying winter temperatures that exist acrossthe country from year to year. Thus, in order to effectively controlagainst a spectrum of snow moulds a relatively high dose may be requiredas well as multiple applications.

Compass™ (trifloxystrobin;(αE)-α(methoxyimino)-2-[[[(E)-[1-[3-(trifluoromethylphenyl]ethylidine]-amino]oxy]methyl]benzenaceticacid methyl ester) is an aromatic dioxime fungicide which has beenapproved for the control of leaf spot, Fusarium patch and brown patchdiseases in turfgrass. Trifloxystrobin is a member of the class ofaromatic dioxime fungicides described in U.S. Pat. No. 5,238,956 grantedto Clough et al.

SUMMARY OF THE INVENTION

One aspect of the invention comprises a composition comprising afungicidally effective amount of a compound have the general formula 1:

and stereoisomers thereof, wherein Y is hydrogen, halo, hydroxy, C₁₋₄alkyl, C₁₋₄ alkoxy, C₁₋₄ haloalkyl, C₁₋₄ haloalkoxy, C₁₋₄ alkylcarbonyl,C₁₋₄ alkoxycarbonyl, phenoxy, nitro or cyano; R₁ and R₂, which may bethe same or different, are hydrogen, optionally substituted alkyl,optionally substituted cycloalkyl, optionally substitutedcycloalkylalkyl, optionally substituted aralkyl, optionally substitutedaryloxyalkyl, optionally substituted arylthioalkyl, optionallysubstituted alkenyl, optionally substituted alkynyl, optionallysubstituted alkoxy, optionally substituted aryl, optionally substitutedaryloxy, nitro, halo, cyano, —NR₃R₄, —CO₂R₃, —CONR₃R₄, —COR₃,—S(O)_(n)R₃ wherein n is 0, 1 or 2, (CH₂)_(m)PO(OR³) wherein m is 0 orI, or R₁ and R₂ join to form a carbocyclic ring system; and R₃ and R₄,which are the same or different, are hydrogen, optionally substitutedalkyl, optionally substituted aralkyl, optionally substituted alkenyl,optionally substituted alkynyl or optionally substituted aryl,and a fungicidally effective amount of a compound having the generalformula 2:

and stereoisomers thereof, wherein Ar represents phenyl or phenylsubstituted with one to two substituents selected from the groupconsisting of chlorine, fluorine, alkyl of one to four carbon atoms andtrifluoromethyl; R₁ represents alkoxy of one to four carbon atoms or—NR₃R₄, in which R₃ and R4 represents hydrogen, alkyl of one to fourcarbon atoms or alkenyl of two to four carbon atoms; R₂ representshydrogen or alkyl of one to four carbon atoms; and X represents oxygenor sulphur.

Preferably the composition comprises additional formulation constituentssuch as the commercial formulation constituents for Rovral Green GT™ andCompass™ as well as similar formulation constituents.

The composition may further comprise a carrier or diluent such as water.According to another aspect, the above compounds 1 and 2 are present inthe composition in a molar ratio of between 9:1 and 30:1, and morepreferably the molar ratio is between 14:1 and 25:1. The compositionsaccording to the invention have useful fungicidal properties, includinginhibiting the infection of turfgrass by a spectrum of snow moulds andin particular pink and gray snow moulds such as M. nivale, T. incarnata,and T. ishikariensis.

According to another aspect, the above compounds 1 and 2 are present inthe composition in a molar ratio of between 1:1 and 6:1 and morepreferably the molar ratio is between 2:1 and 5:1. The compositionsaccording to the invention have useful fungicidal properties, includinginhibiting the infection of turfgrass by dollar spot mould (S.homeocarpa).

According to another aspect of the invention, the compounds 1 and 2comprise iprodione and trifloxystrobin for inhibiting the infection ofturfgrass by a spectrum of snow moulds. According to another aspect, thecomposition is effective when applied such that less than 25% of atreated area of turfgrass is infected by snow mould, by applying thecomposition to turfgrass which is exposed to less than 120 days of snowcover annually.

According to another aspect of the invention, there is provided a methodof using the composition on turfgrass to prevent the infection of snowmoulds or dollar spot infections. In a further aspect the inventioncomprises the method of applying the composition according to theinvention to turfgrass which is subsequently covered with asubstantially impervious tarp. In this aspect, an equal or reducedamount of the active substances may be applied with generally equaleffectiveness in comparison with untarped treatment.

In one aspect the invention comprises the application of formulae 1 and2, preferably as a tank mixture but alternatively in succession, in anamount between 9.08×10⁻² and 0.273 moles, and 4.65×10⁻³ and 1.40×10⁻²moles per 100 m². The said compounds are applied to turfgrass to combatone or more of M. nivale, T. incarnata, T. ishikariensis and S.homeocarpa. Preferably formulae 1 and 2 comprise iprodione andtrifloxyxtrobin applied in an amount of between 30 and 90 g/100 m² and1.9 and 5.7 g/100 m² respectively. Still more preferably formulae 1 and2 comprise Rovral Green GT and Compass or similar commercialformulations.

In a further aspect the invention comprises application of compounds asdescribed above followed by tarping of the field wherein the mouldinfection rate is reduced by at least 90 percent and preferably at least95% in comparison with an untreated control. Preferably only a singleapplication is applied for a given course of treatment.

In a still further aspect the invention comprises the compositions andmethods as described above with a third active constituent comprisingchlorothalonil (Daconil™).

While the invention will be described in conjunction with illustratedembodiments, it will be understood that it is not intended to limit theinvention to such embodiments. On the contrary, it is intended to coverall alternatives, modifications and equivalents as may be includedwithin the spirit and scope of the invention as defined by the presentpatent specification as a whole.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 through 6 illustrate test results for three snow mould funguses,T. ishikariensis, M. nivale, and T. incarnata, on plots covered withsnow for approximately 100 days (FIGS. 1 & 2), approximately 120 days(FIGS. 5 & 6), or trial tarped for 4 months to simulate snow cover(FIGS. 3 & 4). Plots covered with snow had natural snow mould infection,while tarped plots were inoculated with the fungus indicated. The graphsillustrate the percentage of snow mould infection on the tested plot,for different application strengths (in g per 100 m²) of Compass™,Rovral Green GT™ (“RG GT”), alone and in combination.

FIG. 7 illustrates the percentage of S. homeocarpa inhibition ascompared to an untreated test plot, for each of the differentapplication strengths (in g per 100 m²) of Compass™, Rovral Green GT™,alone and in combination.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A composition may be prepared comprising a mixture of iprodione andtrifloxystrobin in the ratio of about 16:1 (w:w) in an aqueous solution,by combining suitable amounts of commercial formulations of Rovral GreenGT™ and Compass™. The said ratio comprises a calculated molar ratio ofabout 19.53:1. The composition may be diluted sufficiently forapplication on turfgrass at a rate of between 30 and 90 g per 100 m²iprodione and between 1.9 g and 5.7 g per 100 m² trifloxystrobin.

A composition may be prepared comprising a mixture of iprodione andtrifloxystrobin in the ratio of about 3:1 (w:w) in an aqueous solution,by combining suitable amounts of commercial formulations of Rovral GreenGT™ and Compass™. The said ratio comprises a calculated molar ratio ofabout 3.93:1. The composition may be diluted sufficiently forapplication on turfgrass at a rate of between 4.92 and 14.76 g per 100m² iprodione and between 1.55 g and 4.65 g per 100 m² trifloxystrobin.

The composition may be applied to turfgrass plots in differentgeographic zones in Canada, including the region subject to more than150 days of substantially continuous snow cover, and regions subject tobetween 90 and 120 days of substantially continuous snow cover. Chemicaltreatments were applied in the late fall at the rate described above,and assessments of snow plots were taken in the spring, after snow coverhad melted off of the trial plots.

FIGS. 1 through 6 illustrate test results for three snow mould funguses,T. ishikariensis, M. nivale, and T. incarnata, on plots covered withsnow for approximately 100 days (FIGS. 1 & 2), approximately 120 days(FIGS. 5 & 6), or trial tarped for 4 months to simulate snow cover(FIGS. 3 & 4). Plots covered with snow had natural snow mould infection,while tarped plots were inoculated with the fungus indicated. The graphsillustrate the percentage of snow mould infection on the tested plot,for different application strengths (in g per 100 m²) of Compass™,Rovral Green GT™ (“RG GT”), alone and in combination.

It was found that a tank mix for application of 250 ml Rovral Green GT™(per 100 m²) and 7.6 g of Compass™ (per 100 m²) provided approximately99% control of T. incarnata, and about 92% control of T. ishikariensis,and 97% control of M. nivale. The tank mixtures described herein thuslead to more inhibition than similar amounts applied separately of theabove components to different plots. Thus, there exists synergy in themixture described above, thereby permitting greater inhibition with alower dosage rate. In the examples herein, the Compass formulationcomprises 50% active substance. Further, in several of the aboveexamples tarped and untarped fields were tested with the tarped fieldsrequiring no greater amount of the composition to achieve effectiveinhibition.

Example 2

A trial was conducted in a region in Canada having a substantiallycontinuous snow cover duration of more than 150 days, with relativelyhigh disease pressure. The mixture of Rovral Green GT™ at 250 ml andCompass™ at 7.6 g (per 100 m²) was applied prior to snow cover, and anassessment conducted after snow melt. Two applications of the mixtureand controls were applied about 10 days apart. After snow melt, thepercentage disease spread of T. ishikariensis and M. nivale weredetected. The Rovral Green GT™ and Compass™ mixture resulted in about25% disease cover, while Rovral Green GT™ at the higher dose rate of 360ml per 100 m² (recommended treatment level) resulted in 71.25% diseasecover, while Compass™ at 7.6 g per 100 m² resulted in 78.75% diseasecover.

Example 3

Three different turfgrass plots infected with dollar spot mould (S.homeocarpa) in three different locations was treated with one of 3.1 gof Compass™ (“Comp”)/100 m², 4.6 g of Compass™/100 m², 62 ml of RovralGreen GT™ (“GT”) or a combination of 3.1 g/41 ml Compass™/Rovral GreenGT™/100 m² on either 14, 21 or 20-21 day intervals.

FIG. 7 illustrates the percentage of S. homeocarpa inhibition ascompared to an untreated test plot, for each of the differentapplication strengths (in g per 100 m²) of Compass™, Rovral Green GT™,alone and in combination.

Fungicidal compositions according to the invention may be supplied in aconcentrated liquid, powder or granular form or any other form commonlyused in the agricultural industry. The fungicidal composition may alsobe supplied in combination as a pre-mix to be diluted to the correctconcentration or supplied as individual components to be combined in atank mixture. Preferably the compositions are diluted with water butother suitable diluents are possible. Other active or inactiveconstituents may also be added.

Although the tested embodiments relate to tank mixtures, improvedresults may also be obtained by separately applying the two activecomponents in close time proximity.

Although this invention has been described in terms of a preferredembodiment, other embodiments that are apparent to those of ordinaryskill in the art are also within the scope of this invention.Accordingly, the scope of the invention is limited only in scope by thefollowing claims and functional equivalents thereof.

The invention claimed is:
 1. A composition for treating fungus infection of turfgrass comprising: a fungicidally effective amount of trifloxystrobin and a fungicidally effective amount of iprodione, wherein said trifloxystrobin and iprodione are present in a molar ratio of between 1:14 and 1:25 or between 1:2 and 1:5 of trifloxystrobin: iprodione.
 2. A composition according to claim 1 in an aqueous solution.
 3. A composition according to claim 1, wherein said trifloxystrobin and iprodione are present in a molar ratio of between 1:14 and 1:25 of trifloxystrobin: iprodione.
 4. A composition according to claim 1, wherein said trifloxystrobin and iprodione are present in a molar ratio of between 1:2 and 1:5 of trifloxystrobin: iprodione.
 5. A composition for treating fungus infection of turfgrass consisting essentially of: a fungicidally effective amount of trifloxystrobin and a fungicidally effective amount of iprodione, wherein said trifloxystrobin and iprodione are present in a molar ratio of between 1:14 and 1:25 or between 1:2 and 1:5 of trifloxystrobin: iprodione.
 6. A composition according to claim 5, wherein said trifloxystrobin and iprodione are present in a molar ratio of between 1:14 and 1:25 of trifloxystrobin: iprodione.
 7. A composition according to claim 5, wherein said trifloxystrobin and iprodione are present in a molar ratio of between 1:2 and 1:5 of trifloxystrobin: iprodione.
 8. A composition according to claim 1 further comprising a fungicidally effective amount of chlorothalonil.
 9. A synergistic composition for treating fungus infection of turfgrass comprising: a fungicidally effective amount of trifloxystrobin and a fungicidally effective amount of iprodione, wherein said trifloxystrobin and iprodione are present in a molar ratio of between 1:14 and 1:25 or between 1:2 and 1:5 of trifloxystrobin: iprodione.
 10. A composition according to claim 1, wherein trifloxystrobin and iprodione are present in a molar ratio of about 1:16.
 11. A composition according to claim 5, wherein trifloxystrobin and iprodione are present in a molar ratio of about 1:16.
 12. A composition according to claim 1, present as a suspension concentrate.
 13. A composition according to claim 5, present as a suspension concentrate. 